Metallic carrier compositions used in the treatment of various disorders have been heretofore suggested and/or utilized (see, for example, U.S. Pat. Nos. 4,849,209 and 4,106,488), and have included such compositions which are guided or controlled in a body in response to external application of a magnetic field (see, for example, U.S. Pat. Nos. 4,501,726, 4,652,257 and 4,690,130). Such compositions have not always proven practical and/or entirely effective, however, for example lacking adequate capacity for carriage of the desired biologically active agent to the treatment site, having less than desirable magnetic susceptibility and/or being difficult to manufacture, store and/or use.
For example, one such known composition, deliverable by way of intravascular injection, includes microspheres made up of a ferromagnetic component covered with a biocompatible polymer (albumin, gelatine, polisaccharides) which also contains a drug (Driscol C. F. et al. Prog. Am. Assoc. Cancer Res., 1980, p. 261).
It is possible to produce albumen microspheres up to 3.0 mcmm in size containing a magnetic material (magnetite Fe.sub.3 O.sub.4) and anti-tumoral antibiotic doxorubine (Widder K. et al. J. Pharm. Sci. 1979, v.68, No. 1, p. 79-82). Such microspheres are produced through thermal and/or chemical denaturation of albumin in an emulsion (water in oil), with the input phase containing a magnetite suspension in a medicinal solution. Similar technique has been used to produce magnetically controlled, or guided, microcapsules covered with ethylcellulose containing antibiotic mitimicine (Fujimoto S. et al., Cancer, 1985, v. 56, (10), p. 2404-2410).
Another method is to produce magnetically controlled liposomes 200 to 800 nm in size carrying preparations which can dissolve atherosclerotic formations. This method is based on the ability of phospholipides to create closed membrane structures in the presence of water (Gregoriadis G., Ryman B. E., Biochem. J., 1971, v.124, p. 58).
The above compositions have a number of serious shortcomings which make their practical medical use difficult, including requirement of extremely high flux density magnetic fields for their control, the lack of technical ability to produce standard magnetically controlled microspheres or liposomes on an industrial scale and the inability to consistently sterilize and store such compositions without changing their designed properties.
To overcome these shortcomings a method for producing magnetically controlled dispersion has been suggested (See European Patent Office Publication No. 0 451 299A1, by Kholodov L. E., Volkonsky V. A., Kolesnik N. F., et al.), the essence of which is that ferrocarbon particles be used as a ferromagnetic material. The ferrocarbon particles are produced by heating iron powder made up of particles 100 to 500 .mu.m at temperatures of 800.degree. to 1200.degree. C. in an oxygen containing atmosphere, with subsequent treatment by carbon monoxide at 400.degree. to 700.degree. C. until carbon particles in an amount of 10 to 90% mass begin emerging on the surface. A biologically active substance is then absorbed on them.
This technology of manufacturing ferrocarbon particles is rather complicated and requires a lot of power. The process is accompanied by oxidation of the ferromagnetic component due to the synthesis of ferrocarbon particles at a high temperature in an oxygen containing atmosphere which dramatically decreases magnetic susceptibility of the dispersion obtained in this way (a 2 times decrease on the average as compared with metallic iron). The magnetically controlled dispersion produced by this technology has relatively low absorption capacity (2.0 to 2.5% of the mass of a ferromagnetic particle is the typical upper limit of absorption of a biologically active substance on such particles).
Furthermore, the magnetically controlled particle itself has a ferromagnetic component of a spheroidal form with a thread-like carbon chain extending from it. The overall size of such a composite particle is less than 2.0 .mu.m. Such structure of the ferrocarbon particle predetermines its relatively low absorption capacity, and also leads to breaking of the fragile thread-like chains of carbon from the ferromagnetic component during storage and transportation as well as difficulties during packaging because of its looseness.
Further development in this field could thus still be utilized.